Two music fans are taking on the music industry to try to stop the increase in CDs with hidden anti-copying devices, which they say are often defective.

The unnamed fans, from southern California, have begun legal proceedings against the five major record companies in an attempt to get the copy-protected CDs banned or clearly labelled.

They say some CDs with the new technology have inferior sound quality or do not play at all, can jam disk drives and infringe customers' rights to make personal copies.

Some fans reported problems with Celine Dion's latest CD

Record companies have introduced the technology to stop widespread illegal copying, which they describe as "theft" and blame for falling sales.

The anti-copying locks are designed to stop users copying tracks on to their computers, from where they can be put on to any number of blank CDs or sent to any number of fans over the internet.

But the technology is flawed, according to Alan Mansfield, a lawyer representing the fans - and consumers have no way of knowing which CDs have it installed.

"Some versions of the Aerosmith greatest hits CD have the copy-protection technology and some don't," Mr Mansfield said.

"Because it's not in all CDs, it's like Russian roulette."

Music creators have the right to protect their property from theft, just like owners of any other property

Cary ShermanRecording Industry Association of America

When played, the CDs can skip tracks, were worse quality than normal and could refuse to play at all, Mr Mansfield said.

The problems "interfere with customers' legal rights to back up, play or transfer their own music for personal, non-commercial use to other playback mediums", he said.

The music industry has reported a 50% rise in pirated CDs in 2001. That has coincided with a 5% slump in music sales around the world.

The anti-copying measures are also partly in response to illegal song-swapping internet sites like Napster, through which millions of fans could access a song that just one person had copied from one CD.

'Unlawful'

"Music creators have the right to protect their property from theft, just like owners of any other property," said Cary Sherman, president of the Recording Industry Association of America trade group.

"Motion picture studios and software and video game publishers have protected their works for years, and no one has even thought to claim that doing so was inappropriate, let alone unlawful."

Fans have also reported problems with CDs by Celine Dion, Natalie Imbruglia, Shakira, Westlife and 'N Sync, among others.

Such CDs started to come on to the market about six months ago, but are not thought to represent the majority of CDs on sale.